Phonograph reproducer



Patented Nov. 15, 1927;

UNITED lvSTATES PATENT oEFlcE.a

HEBER s. NELSON, E sALT LAKE oiTY,`UTA1 1, AssIGNoR oF ONE-FOURTH ToROBERT MURRAY STEWART, 0E sALT LAKE CITY, UTAH.

rHoNoGRAPH Application filed April 9,

. reproduce the music, voice, .sounds of whatever is recorded', thusIproviding an instrument for such purposes which will be extremelysensitive to actuating vibratory changes.

Another object is to provide av spool for the coil ofwire, whichy willnot permit eddy currents of the transformer type.

Another object of the invention is to use' a single spool or winding and'yet obtain the combined magnetic action of four pole pieces on thevibrating armature.

Another object'isto provide a-means of centering, balancing andadjusting the armature to the' most sensitive position, so as to preventthe armature 'from sticking to the pole pieces and to produce throughthe am. pliier with loudness and distinctness, with-` out distortion,such articulate vor other sounds' as may be imbedded on the surface ofya phonograph record.

With the foregoing and other objects `in view, the invention consists ofcertain novel features of construction, combination and `arrangement ofparts, as will be more fully '35 described and. particularly pointed outin the appended claims. c

In order that my invention may be fully understood, I will proceed todescribe it, having reference to the accompanying draws.

40 ings, in which- Figure 4 is a side-elevation of an electromagneticpick-up constructed inaccordance with my invention. vFig. l1 is atransverse section of the same, on the' line 1 1 Fig'. 4c

l and looking in the direction indicated bythe arrows on said line. Fig.2 is a longitudinal 4section of the same,through the center of thearmature and the stylus bar, on the line lof 2 2 of Fig. 1 and lookingin .thedirec- 5o tion indicated by the arrows on said line.

Fig. 3 is a cross sectional view ofthe same,'

through the cent/er, on the line 3 8 Fig. 4.

and looking in the direction indicated by the arrows thereon; Fig. 5 isan enlarged cross sectional view showing the method of pivot'- 'blocks band b", which are secured to the lThis frame is of non-magneticmaterial.

REPRoDUoER.

ing the armature; Fig. 5^ is a side elevation of the armature and shaft.Fig. 6 is an enlarged cross sectional view showing a modied means ofpivoting the armature. In said drawings H designates a permanent magnetof circular form, to its'extremities or poles h and ff are secured the UA .shaped pole pieces P and P by'gneans of screws lc c; these polepieces support the spool S, onl which is wound the wire forming the coilof wire, the number of turns of wire being dependent upon the impedanceof the circuit in which the pickup is to be used. This .spoolconsists ofa non-magnetic oblong Itube with ovalend pieces, the tube is slotted atz Fig. 5 upon its upper side and its ends separated so as to preventeddy currents from eii'ecting the magnetization of the armature A. Thisspool is held in p'lacel by 192e. serial No. 100,961.

spool Aat each end and fit into recesses cut into the pole pieces P andP at each of their four corners. This armature is supported b means of ashaft E. This shaft/,is supported at its ends by being run throughapertures in the walls of the tube. Thel armature has slotted recessesstamped into it across its exact center to admit the shaft E. One end ofthe armature is connected to the stylus bar B. The stylus bar is slottedat y to receive the armature. The stylus bar is pivoted by means ofscrewsp p', Fig. 1, engaging in lugs n n. These screws p p are supportedby the lugs o o from the frame F.

90 The pole piece P is secured to itl by screws A 1 11,'which hold the'entire unit in the case.

-Thescrew t is. also tapped into the fra-me.

The screws t t are for the purpose of adjusting the tension of thesprings sys which cen. ter and balance thel armature in its mostsensitive position. The screws t t and the stylus bar' are provided withshort lugs over whiclrthe springs s s are placed to keep them4from'moving out of allgnment. `The 100 ends of the wire from the spoolS are solderedtothe standards c c. These standards are provided withsuitable set screws -for connectlng wires to the amplifier.. Theyl arealso suitably insulated from each other and from the frame. Anon-magnetic cover 'D 1s provided to 'protect the various working parts.

The operation of the electromagnetic pick- `upiis as follows: The stylusbar B is caused to vibrate by the needle following the groove engravedin the record. The stylus .bar vibrates the armature, which is polarizedby the permanentmagnet H through the pole 'pieces P P', thus inducing acurrent or electrical impulses in the coll, which is transmitted to theamplifier. The poles of the U shaped pieces lP P being of opposite po-.larity adjacent to that end of the armature which is of north polaritywill operate-one to repel and the other to attract that end of thearmature. .will repel and the other attract'the opposite end of thearmature, thus establishing magneticequilibrium and polarizingthearmature.' It follows that any slight vibration of the armaturedisturbs the e uilibrium of the magnetic circuit. above constructionwill cause the articulate or other sounds which are recorded to bereproduced with great force and distinctness,

owing, mainly to the attractive action of the polarized armature uponthe -poles of the' magnet, and this result is obtained when only twoopposite poles are u'sed as Well as when four are present.l Theemployment of four poles as shown', is preferred, however, be'-1 causein this construction the, attractive and repulsive force of' both endsvof the armature is used. Iffor any purpose astronger field magnetis'desired the-permanent magnet may be re laced by an electromagnet. Y

It 1s obvious that the'instrum'ent may-be used as arecorder, for thereason that when' the. coil is" connected to thev output of a recordingcircuit and when a current or 'elec- Atrical impulse is sent throughlthe coil W, it

magnetizes the armature A. It follows that in the passage of anundulating current eo j . I claim is: j

. of the phonograph type-,comprising a field through the coil, thearmature will be attracted witha force equal to the repulsion andattraction of all four poles, and that the vibratory motion thusproduced -will be transmitted through'the stylus bar to: the needle orengraving tool.

T he instrument will thus be seen to be lequally advantageous for u'seas a recorder; 'the magnet having anl intensifying' action A f1'. Anelectromagnetic reproducing'd'evice magnet, double pole pieces for.saidv field magnet, `one lmbof'each pole 'piece acting Similarly one ofthe poles .It is o vious that ,the

upon one end of an armature, and the other.'

`wire having freedom of motion about its axis and pivoted in said tube,said core constituting or being identical with said armature, a stylusbar capable of transmitting the vibra, tory motion of the needle tothearmature, or the reverse. f

recording device of the phonograph type comprising a field magnet, onelimb of each pole piece acting upon one end of an armature; and theother limb of cach pole piece acting upon the opposite endof saidarmature, a coil of wire, a split non-magnetic tubewithin said coil ofwire, a shaft within the core of said 'coil of wire having freedom ofmotion-about its `axis and piv' otel'l in said tube, said coreconstituting or being identical with said armature, a stylus bar capableof transmitting the vibratory motion ofthe armature through the stylusbarto the needle or engraving tool.

3..An. electromagnetic reproducingand recording device comprising apermanent magnet, two pole pieces attached to the permanent magnet, acoil of wire wound around a -nonmagnetic spool to an impedance Suit-'fable to the electric circuit in which the device is to be used, acentrally pivoted armature operating between the four poles of the two.

pole pieces and energized by them and connected to a stylus bar with aflexible device for maintaining the balance of the armature- 2.' Anelectromagnetic reproducing and.

4. An electromagnetic reproducing and recording device comprising a bodyring and casmg, aA .permanent magnet, two pole 'pieces forming fourpoles, a. coil of wire wound around a nonmagnetic-tube to form 'a spoolhaving through its center an armature which is supported by means 'of ashaftpivoted through its center inthe walls of the' tube, and connectedwith a Stylus bar which is capable of being adjusted.

5. An electromagnetic reproducing and recording 'devicefof thephonograph type comprising a body ring, a casing, a-permanent magnetmounted therein, two U shaped pole pieces attached to the permanent,magnet, a coil of wire wound to an impedance '(suitable to the electriccircuit in whiclrthe device is tobe used) around a nonmagnetic slottedtubeshaving nonmagnetic end pieces thus forming a spool which spool isfastened within the two pole pieces, an armature within the spoolcentrally, pivoted with a1 shaft which is supported in the walls' ofthenonmagnetic tube, said armature being connected toan adjustable stylusbar which will iexibl'y maintain the armature inv a properly balancedVposition withinsaid spool.l

6. Anelectromag'netie phonograph reproducing and recording devicecomprising an adjustable stylus bar attached to an armature that pivotson a Shaft said shaft passing through the center of said armature andsupported in holes in the walls of a slotted nonmagnetic spool aroundwhich'is wound a coil of wire, said armature extending beyond the endsof the spool and energized by thefour poles of two U shaped pole pieceswhich arel secured to a permanent magnet, said permanent magnet beingsecured to a body ring in which are also secured two insulated contactlugs for connecting with an electric circuit.

7. An electromagnetic phonograph r'eproducing and recording devicecomprising a stylus bar pivoted to a body ring with a device .foradjusting said stylus bar, said stylus bar attached to an armature Whichpivots on a shaft passing through its center thus allowing for a rotaryrathert n a lateral movement of the armature7 said shaft being spportedin holes in the Walls of a nonmagnetictube, said tube being slotted inorder to prevent eddy currents of the transformer type, said tubetogether with nonniagnetic end pieces forming a spool around which iswound, to an impedance suitable to the electric circuit in which thedevice is to be used, acoil of wire, the ends of the armature eX-tending beyond the ends of the spool and energized by the four poles ofthe two U Shaped pole pieces; said poles being secured to a permanentmagnet .which is securedto a body ring in which arc also secured two inisulated contact lugs for connecting with an electric circuit.

In'test-ilnony whereof, I have hereunto sei'l i my hand.

HEBER S. NELSON.

